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Abstract

Introduction
Preventable hospitalization for congestive heart failure (CHF) is believed to
capture the failure of the outpatient health care system to properly manage and
treat CHF. In anticipation of changes in the national health care system, we
report baseline rates of these hospitalizations and describe trends by race over
15 years.

Methods
We used National Hospital Discharge Survey data from 1995 through 2009, which
represent approximately 1% of hospitalizations in the United States each year.
We calculated age-, sex-, and race-stratified rates and age- and
sex-standardized rates for preventable CHF hospitalizations on the basis of the
Agency for Healthcare Research and Quality’s specifications, which use civilian
population estimates from the US Census Bureau as the denominator for rates.

Results
Approximately three-fourths of the hospitalizations occurred among people aged
65 years or older. In each subgroup and period, rates were significantly
higher (P < .05) for blacks than whites. Only black men aged 18 to 44
showed a linear increase (P = .004) in crude rates across time.
Subpopulations aged 65 or older, except black men, showed a linear decrease (P
< .05) in crude rates over time. Age- and sex-standardized rates showed a
significant linear decrease in rates for whites (P = .01)
and a
borderline decrease for blacks (P = .06)

Conclusion
Before implementation of the Patient Protection and Affordable Care Act, we
found that blacks were disproportionately affected by preventable CHF hospitalizations
compared with whites. Our results confirm recent findings that preventable CHF
hospitalization rates are declining in whites more than blacks. Alarmingly,
rates for younger black men are on the rise.

Introduction

Studies and expert committees have identified conditions for which many
hospitalizations could be avoided if patients received early access to
good-quality health care (1,2). These conditions have been labeled
ambulatory-care–sensitive conditions (ACSCs) (1,2) and are used by the federal
government as Prevention Quality Indicators (PQIs) (3). Congestive heart failure
(CHF) is one such ACSC (3).

Clinical guidelines are available for the diagnosis and management of CHF
(4,5), and evidence exists that physicians could better adhere to these
guidelines (6). Other ways to reduce the likelihood of hospitalization are
disease management programs (eg, increased follow-up) and self-management
programs including symptom monitoring, weight monitoring, or medication dosage
adjustment (7,8).

Prevention of future hospitalizations can occur even before symptoms of CHF
occur. Evidence-based strategies in the outpatient setting for these patients
include control of hypertension and low-density lipoprotein cholesterol, use of
angiotensin-converting enzyme inhibitors if appropriate, smoking cessation,
physical activity, weight management, and diabetes management (4,9).

The 2010 Patient Protection and Affordable Care Act (PPACA) aims to increase
access to outpatient care and improve the quality of such care through
implementation of evidence-based outpatient management systems and strategies
(10). We used national hospital survey data to describe pre-PPACA baseline rates of
preventable CHF hospitalizations and describe racial differences in these rates
over time. Although others have examined similar trends over time (11,12), 1
group of researchers recently reported a decline in national CHF hospitalization
rates for blacks and whites aged 65 years or older (11). We extend these recent
findings by examining more years of data and by examining both younger and older
adults. We anticipate our results being useful now and in the future to help
monitor the effect of changes in the national health care system.

Methods

Data source and definitions

We used data from the 1995 through 2009 National Hospital Discharge Survey (NHDS)
conducted by the National Center for Health Statistics (NCHS) (13). Details of
the sampling design for each year of the study are provided on the NCHS website
(www.cdc.gov/nchs/nhds/nhds_sample_design.htm).
For the 1995 through 2007 data, the sample included 501 to 525 hospitals;
the average unweighted response rate was 89%. In 2008 and 2009, NCHS had only
enough funding to collect data from 239 hospitals; the unweighted response rates
were 86% to 87%. At the final stage of sampling, the NHDS selects a systematic
random sample of inpatient discharge records from each participating hospital,
representing approximately 1% of all hospitalizations in the United States.

We calculated population-based hospital discharge rates according to
specifications published by the Agency for Healthcare Research and Quality (AHRQ)
for PQI #8, congestive heart failure admission rate (14). To be defined as a
preventable hospitalization, the numerator consists of all nonmaternal
discharges of people aged 18 years or older with the following International
Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM)
principal diagnosis codes: 398.91, 428.0, 428.1, and 428.9. Because of ICD-9-CM
coding changes in 2002, AHRQ requires that principal diagnosis codes of 402.01,
402.11, 402.91, 404.01, 404.03, 404.11, 404.13, 404.91, and 404.93 be included
in the numerator only through September 30, 2002. After that, AHRQ requires that the
following principal diagnoses codes be included in the numerator: 428.20,
428.21, 428.22, 428.23, 428.30, 428.31, 428.32, 428.33, 428.40, 428.41, 428.42,
and 428.43. Specifications require that maternal discharges identified using
major diagnostic category 14 (pregnancy, childbirth, and puerperium) be excluded
from the numerator. The NHDS data are not grouped by major diagnostic codes;
thus, maternal discharges were identified according to another method that uses
ICD-9-CM codes alone (15). AHRQ further specifies that preventable
hospitalizations for CHF exclude from the numerator transfers from another
institution including a hospital, skilled nursing facility, or intermediate care
facility (database missing this information before 2001) and discharges with
cardiac procedure codes in any field. Excluded were people hospitalized with
procedures such as implants and maintenance of pacemakers, surgical procedures
for repair of heart valves, revascularization, coronary bypass surgery, heart
transplants, and other such procedures. Because of these exclusions, the most
serious cases of CHF were eliminated, leaving those hospitalizations that are
believed to be most preventable. People who received diagnostic testing (eg,
echocardiograms, catheterization, stress testing) or who received nonsurgical
treatments (eg, diuresis, medication adjustments) were included in the
numerator. Eligible hospitalizations defined as above will hereafter simply be
called hospitalizations for CHF.

The denominators for the rates are the civilian population estimates from the
US Census that are published by NCHS as part of the documentation package
for each year’s NHDS database (13).

We used the confidential database for this analysis, which allowed us to use
sampling design variables to calculate standard errors around estimates. The
descriptor of primary interest was race, which was reported for approximately
80% of the records. We used 2 categories of race for this analysis: white or
black (we did not separate out whether someone was Hispanic because of the large
number of discharges that were missing this information) (16). We also created
an “other” category that consisted of Asian, American Indian, Alaska Native,
Eskimo, Native Hawaiian, Pacific Islander, and any other race that was specified
on the form. Race was considered missing if the medical record abstract form had
“not stated” checked or if multiple races were recorded. The multiracial category
was included in the missing category because it has only been coded in the
database since 2000 and accounts for a small percentage of hospitalizations (eg,
during 2005-2006 it was 3%). Although we used the “other” category in a
description of hospitalizations for CHF, we did not use it for our main analysis
because the sample sizes were small with broad confidence intervals, especially
after stratification by age and sex. The geographic areas included in
the study were the 4 census regions: Northeast, Midwest, South, and West (17).
For insurance type, we used Medicare, Medicaid, private insurance, and other. We
used only the principal source of payment to derive these categories. “Other”
included types such as other government insurance, self-pay, hospitalization
without a charge, and workers’ compensation.

Statistical analysis

We estimated the total weighted number of hospitalizations for CHF each year
from 1995 through 2009 for people aged 18 or older. Because we analyzed only
records for which CHF was the primary reason for the hospitalization
and because we were interested in studying a smaller subgroup of the population
(ie, blacks), we combined 2 years of data to obtain a larger number of reliable
estimates for 1995 through 2006. Because half samples were used in 2008 and
2009, we combined 3 years of data to obtain reliable estimates for 2007 through
2009. We combined the smallest number of years to achieve relative standard
errors that were smaller than 30% for each age-race-sex stratum. Consequently,
we had 7 analytic periods (1995-1996, 1997-1998, 1999-2000, 2001-2002,
2003-2004, 2005-2006, and 2007-2009). We summed census population estimates over
these same periods and used them to calculate rates per 100,000 population.

Because we were interested in describing the burden of hospitalizations in
various population subgroups, we report crude rates by age (18-44, 45-64, and
≥65), sex, and race. We also directly standardized rates for each period
and racial group by age and sex using the 2000 Census population as the
standard.

We used SUDAAN (Research Triangle Institute, Research Triangle Park, North
Carolina) to calculate 95% confidence intervals around the estimates of the
number of hospitalizations for CHF. We did not develop confidence intervals
around the denominators because they were derived from a census of the population.
We tested differences between subgroups using z tests; significance was
set at P < .05. We used simple linear regression, weighted by the inverse
of the variance of each year’s rate, to test for linear time trends for each
study subgroup and for the standardized rates. We used the t test to
determine whether the slope was significantly different from zero. We did not
test for nonlinear trends because of the complexity of interpreting curves with
a restricted number of points and the difficulty of explaining transformed rate
data.

Results

During 1995 through 2009, there were 121,741 records with preventable
hospitalizations for CHF among adults in the NHDS sampled
hospitals. This translates to a weighted number of
15,208,518 hospitalizations
for adults in the United States during the 15-year study period, an average of
1,013,901 each year.

Approximately three-fourths of preventable hospitalizations for CHF were
among people aged 65 or older (Table 1). In 2007 through 2009, as in every other
period, a higher percentage of these hospitalizations occurred for women
(53%) than for men (47%). The South had the highest percentage of
hospitalizations (37%-39%). The West had less than 15% of hospitalizations. The
most frequent payer was Medicare, ranging from 73% to 77%, depending on the period. No other payer came close to this percentage; for example, in 2007
through 2009, Medicaid paid for 8%, private insurance paid for 13%, and all
other types of coverage accounted for 5%.

For women, the crude rates for preventable CHF hospitalizations increased
with
age for both racial groups in each period (Table 2). In all subgroups
of women, the crude estimates for black women were higher than those for white
women during all 7 periods (Table 2). For white women, we found a
significant decreasing linear trend for those aged 45 through 64 and for those
aged 65 or older. For black women, we found a decreasing linear trend for those
aged 65 or older (Table 2). For white and black women, the highest rate occurred
among those aged 65 or older; it peaked in 1997 through 1998 for whites
(1,903.8/100,000) and in 1999 through 2000 for blacks (3,303.6/100,000).

Crude rates for preventable CHF hospitalizations among men increased with age
during every period (Table 3). In all subgroups of men, the point estimates
for black men were significantly larger than for white men (Table 3). We found
an increasing linear trend in rates for black men aged 18 to 44. For white men
aged 65 or older we found a decreasing linear time trend (Table 3). For white
and black men, the highest rate occurred among those aged 65 or older; it peaked
in 1997 through 1998 for whites (1,932.6/100,000) and in 1995 through 1996 for
blacks (2,706.5/100,000). For both women and men, the ratio of the rates for
blacks compared to the rates for whites was highest in the youngest age group
(~6.5) and lowest in the oldest age groups (~1.5).

Age- and sex-standardized rates also show that blacks had higher rates of
hospitalization for CHF than did whites (Figure). The negative linear trend for
whites was significant and the negative trend for blacks was of
borderline significance. The slopes for whites and blacks were not significantly
different from each other.

Figure. Age- and sex-standardized preventable
hospitalization rates for congestive heart failure in the United States across 7
periods. Error bars represent 95% confidence intervals. There was a
negative linear trend for whites (β = −14/100,000; P = .01) and
a borderline decrease for blacks (β
= −19/100,000; P = .06). The slopes for blacks and whites were not
significantly different from each other. Source: National Hospital Discharge
Survey, 1995-2009. [A tabular version of this
figure is also available.]

Discussion

We studied hospital discharges from 1995 through 2009 and found that blacks
in every age and sex subgroup had significantly higher rates of hospitalization
for CHF than did whites. For both women and men, the ratio of the rates for
blacks compared to the rates for whites was highest in the youngest age group
(~6.5) and lowest in the oldest age groups (~1.5). Our results generally confirm
recent findings (11) demonstrating a significant declining linear trend in CHF
hospitalizations for people aged 65 or older. However, we did not find that
black men in this age group experienced these same declining rates. In fact, we
found a significant increasing linear trend for black men aged 18 to 44.

Other investigators have reported racial differences in preventable CHF
hospitalizations. Using hospital data from 1991 through 1998 in California for
people aged 20 to 64, Davis and colleagues found that non-Hispanic black men and
women had unadjusted rates that were 4.1 and 5.5 times higher, respectively,
than those for their non-Hispanic white counterparts (18). Using 1997 data from
22 states, Laditka and others studied a similarly aged population of
non-Hispanics and found that black men were 3.4 times as likely to be
hospitalized for CHF as white men, and black women were 6.5 times as likely to be
hospitalized as white women (19). In 2003, Russo et al studied hospitalizations for
people aged 18 or older from 23 states and found that age- and sex-adjusted
rates for non-Hispanic black men and women combined were 2.5 times higher than
those for non-Hispanic white men and women (20). Using Medicare data from
Maryland in 2006, O’Neill and colleagues (21) found that adjusted rates for
blacks were 60% higher than for whites. Using the 1995 through 2004 NHDS but
with a different case definition than in our study, Zhang and Watanabe-Galloway found that blacks aged
65 or older had higher CHF hospitalization rates than did whites (12).

Among adults aged 45 to 84, blacks have approximately twice the incidence of
CHF as whites (22), and blacks with CHF may have more comorbidities such as
uncontrolled high blood pressure (23,24). This higher incidence and
comorbidities may be reflected in the higher hospitalization rates among blacks
(24). Furthermore, blacks, when affected by heart failure, experience a unique
epidemiology and natural history (ie, disease occurring at an earlier age
resulting in more substantial left ventricular dysfunction), which also may
contribute to these increased rates (25). The cost of medications and type of
insurance may create barriers to appropriate care, for example, by leading to
the underuse of dietary and medication therapies (26-28). Blacks are less likely
than whites to receive medical care such as appropriate diagnostic procedures,
thrombolytic therapy, and revascularization procedures for acute coronary
syndrome (29), and these delays in receiving quality care could help explain the
higher hospitalization rates for blacks.

Our study contributes to the literature in the following ways: 1) we confirm
a declining linear trend in CHF hospitalizations in much of the older population
using data from hospitals sampled throughout the 50 states and the District of
Columbia, 2) we provide national age- and sex-specific rates for multiple periods, thus establishing a baseline for future monitoring of health
disparities, 3) we provide confidence intervals (calculated appropriately from a
confidential database that includes design variables) showing the degree of
certainty or uncertainty of point estimates and allowing judgments about the
significance of differences between subpopulations, and 4) our results cover all
adults and extend through 2009.

Our study also has several limitations. First, race was not reported for 17%
to 21% of the CHF hospitalizations. These missing values likely are
disproportionately occurring in the white population because hospitals that did
not report race had a higher proportion of white discharges than hospitals that
did; thus, our results may overestimate the differences in rates between blacks
and whites (16). We believe that because the differences between racial groups
are already large, it is unlikely that the distribution would be so skewed
as to eliminate the differences between the 2 groups (16). For example, using
data from 2005 through 2006, and assigning all missing hospitalizations to
whites, we observed an increase in the rate for whites (from 353/100,000 to
461/100,000). Even after such an extreme assumption, blacks still have a higher
rate (601/100,000) than whites. Also, because our findings are supported by many
other researchers (12,19-22), we believe that these differences are likely real.
Second, starting in 2000, NCHS allowed abstractors to record multiple races and
to record them as such in the database, likely leading to some people who would
have been classified before 2000 as either black or white now being classified
as multiracial. Because only 3% of the records have race classified as
multiracial, the effect is likely minimal. The difference between blacks and
whites is smaller in our study than in previously published studies,
most likely because we did not exclude all Hispanics from our groups of blacks
and whites (other studies used the classification of non-Hispanic white compared
to non-Hispanic black). Finally, as required by AHRQ’s definition of a PQI, we
were unable to exclude CHF hospitalizations that occurred because of transfers
from another facility (ie, hospital, skilled nursing facility, or intermediate health
facility) for the years 1995 through 2000 because transfer data were not
collected during those years. However, on the basis of the years for which
transfer data were available, we believe that excluding them from 2001 through
2009 created only a small error, given that transfers accounted for
approximately 3% of CHF hospitalizations.

Our results and those of others indicate that CHF hospitalizations are
higher among blacks than whites. It also appears that rates are dropping in a
linear fashion for whites, mainly because of decreasing rates in the population
aged 65 or older. It is alarming that in most subpopulations of blacks, rates are
either remaining level or are increasing; most disturbing is the increasing
linear trend for younger black men. Primary care strategies such as heart
failure disease management programs (8) and aggressive comprehensive risk factor
management (4,9) may help close this gap between blacks and whites and younger
and older Americans. We advocate for continuing surveillance of these trends and
suggest that these preventable hospitalizations may be a useful metric for
monitoring changes associated with health care reform. In addition, further
studies aimed at examining the potential reasons for such racial differences are
needed. These studies will likely require merging data from various data sources
and using multivariate analyses.

National Hospital Discharge Survey questionnaires, datasets, and related
documents. US Department of Health and Human Services, Centers for Disease
Control and Prevention; 2011. http://www.cdc.gov/nchs/nhds_questionnaires.htm.
Accessed November 10, 2011.

Abbreviation: CI, confidence interval.a Totals are less than totals for the other characteristics because
of missing values: 327,422 (16.9%) in 1995-1996; 377,994 (17.7%) in 1997-1998;
428,915 (19.7%) in 1999-2000; 395,890 (19.4%) in 2001-2002; 422,471 (20.5%)
in 2003-2004; 393,172 (19.2%) in 2005-2006; and 516,833 (18.3%) in 2007-2009.b Totals are less than totals for the other characteristics because
of missing values: 23,591 (1.2%) in 1995-1996; 18,101 (0.8%) in 1997-1998;
15,044 (0.7%) in 1999-2000; 26,372 (1.3%) in 2001-2002; 28,155 (1.4%) in
2003-2004; 25,687 (1.3%) in 2005-2006; and 47,240 (1.7%) in 2007-2009.

Table
2. Crude Preventable Hospitalization Rates for Congestive Heart Failure per
100,000 Population Among Women, by Age and Race, National Hospital Discharge
Survey, United Stated, 1995-2009

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